To prevent timber from rotting and degrading under harsh environmental conditions, it is common practice to pressure treat the wood with chemicals which have the ability to considerably slow down its natural decomposition. Such pressure treated timber is normally guaranteed by the manufacturer for a minimal useful life and it is common practice to express the warranty conditions onto a label or a tag fastened on each timber piece produced by the mill. Presently, tagging the timber is accomplished manually by using a hand operated stapler gun for fastening individual tags to timber pieces with wire staples. Accordingly, this seamingly simple operation is time consuming, which constitutes a disadvantage.